Pentabromindigo.



unrrnn STATES PATENT" OFFICE.

ALBRECHT sonivrrnr AND-KARIQTHIESS, or HoonsT-oN-THEamm, GERMANY, AS-sreuoas T0 FARBWERKE VORM. MEISTER LUCIUS & BRU'NING, on-HooHs'noN-THE-MAIN, GERMANY, A CORPORATION cream/may.

PENTABROIVIINDIGO.

No Drawing.

To all whom it may concern Be it known that we,ALmu :o1i"r SoI-rMIn'r,

'Ph. D., and KARL TI-IIESS, Ph. D., citizens of the Empire of Germany,rcsiding atII'ochston-the-Main, Hesse-Nassau,"Prussia, Germany, haveinvented certaln new and useful Improvements in Pentabromindigo, ofwhich the fUllOWlTlglS a specification.

It indigo or a bi'olninated indigo, such as mono-, di-, triortetra-brom1nd1go,as treated at raised temperature with an excess ofstructural formula of the new pentabromindigo is very likely as follows:

This pentabromindigo dyes in the vat a blue ofa considerably moregreenish tint than tetrabromi'ndigo, which factis particularly wellperceivable in artificial light.

Example I: 26 parts by weight of indigo are stirred,- while being wellcooled, in 260'- parts ofbromin, and the mixture is gently and graduallyheated whilestirring, and

then the 'heating'is continued, under pres sure, for some hours, up to80 G; Then the excess of bromin is removed by; means of a current, ofair 01' by washing with. carbon tetrachlorid, and the remaining greenishblack mass, which Sllbstill lt-ifllly consists of a perbromid of apentabrominated indigo, is heated with a. solution of bisulfite,filtered and washed with hot water. The pentabromindigo thus powder, CI-I N O Br containing 59.81% (theoretically, 60.88%) of bromin. Thisproduct dissolves in concentrated sulfuric acid with a pure blue color,and incold anilin with a blue color, thereby being distinguished fromtetrabromindigo which. dissolves with agreenish hue. It is also muchmore readily soluble in organic solvents than triand tetrabromindigo,and when Specification 6f Letters-latent.

obtained forms a'dark blue Patented Aug. 19, 1913.

Application filed July s, 1908. Seria1No. 4.-42,625;-

oxidized, for instance"by means, of nitric acid in presence of glacial.acetic acid, it yields a mixture 'of 4-5.7-tribron1isatin melting at257 C. and 5.7-di-bromisatin melting at 249-250 C- whereas-thepentabromindigo described in British Patent No. .10326/07 yields on 1oxidation a- "mixture of a diand tribromisatin each 0011- taining-onebroinin-atom in m (6) position to the NH- group. This pentabrom'indigodyes in the vat a considerably more greenish blue than thetetrabromindigo, and the pentabromindigo described in British Pat: entNo. 10,326 of1907, which fact is particularly recognizable in artificiallight.

ExampleII: 21 parts by weight of dibromindigo containing IOPIIISULIICQ-36.6% bromin are introduced, while well cooling, into'lSO parts ofbromin, in which 1-2 parts of iodin may be dissolved to advantage, andthe mixture is heated for some hours, under. pressure up' to 80 C. Theprocedure for finishing the product is as perExample' I. Thepeiitabrominated indigo thus obtained contains 60.04% of broininandshows the same properties as-the dyestutf obtained as per Example I.

Example III: parts by weight of di bromlndigo contalnmgfor instance 38%of bromin are'stirred' in about252 parts of concentrated sulfuric acidof 66 B6. Then about 150 parts of bromin, in which 2 parts of iodin maybe dissolved to advantage, are

added while cooling. The mixture is heated for some hours in the refluxcooling apparatus up to 70-80 C; After finishingt-hc bromination theexcess of bromin isexpclled bv distillation or by means of a current ofair. The greenish-black mass substantially consists of a perbrk-nnid ofa pentabromb nated indigo. To obtain therefrom pentabromiudigo, the massis pi'esscdon bisulfite and ice, filtered ofi'and washed with water.

The pentabrolninated indigo thus obtained 7 contains 59.88% of brominand shows the same properties as the dyestulf obtained as per Example I.I

In general it is sufficient and necessary that indigo,.or itsbromsubstitution products obtained by brominatiug indigo, be treated,preferably while heating, with an excess of bromin of at least. one atomof bromin above that quantity of bromin which, is required for thepcntahalogenation.

Having now described our invention, what we claim 1sz' As a new product,1 structural formula: J 3 Br oo 1 co 1 Br(3) pentabromindigo of being aday ri-t-b1ue powder, soluble in concentinted sulfuric acid with a bluecolor and in' 1:2: cold aniiin aiso with a blue color, much more readilysoluble in organic solvents than tri'-' and tetrabroniindigo; yieldingon oxidation, 7 4

by means of nitric acid in glacial acetic acid,

a-mixture of 4.5.7-triand 5.7 -di-bromisabin.

In testimony whereof, we aflix our sigma- 15 tures in presence of twowitnesses.

ALBRECHT SCHMIDT. KARL THIEssr Witnesses:

JEAN GRUND, CARLIGRUND.

